First announced more than a year and a half ago, Citrix has finally released a 1.0 version of its inaugural client hypervisor. Citrix XenClient 1.0 narrows the gap between offline and online virtual desktops and extends the benefits of desktop virtualization to mobile platforms by increasing flexibility for users and improving security and control for IT.

Originally known as Project Independence, XenClient is a high-performance, bare-metal or Type-1 hypervisor that runs directly on the client device hardware, dividing up the resources of the machine and enabling multiple operating systems to run side-by-side in isolation. As you might expect, XenClient is based on the 64-bit version of the Xen hypervisor. Citrix is officially supporting client VMs running 32-bit Windows XP and Vista as well as 32- and 64-bit versions of Windows 7.

XenClient Express, the free edition, is being made available so individuals and organizations can download and use XenClient on as many as 10 machines. However, Citrix support for Express will be limited and there is no centralized management available with this version. Official support is being offered only when XenClient is used within the Enterprise or Platinum editions of Citrix XenDesktop. In addition to increased support, XenDesktop offers XenClient centralized management, image delivery, and backup, which is performed by a server component called Citrix Synchronizer.

Dave Bartoletti, a senior analyst with the Taneja Group, is impressed with what he has seen so far. "If VMware is doubling down on VDI (server-hosted), then Citrix is definitely doubling down on endpoint virtualization. I think they have nothing to lose by offering even a simple client hypervisor for testing, and the buzz could drive quite a few companies to grab XenClient and download the Receiver."

Bartoletti added that Xen VMs are still necessary on a server somewhere. However, he believes the Citrix marketing materials step users through the process quite well.

Citrix announced the following new enhancements to XenClient 1.0 and Synchronizer since the last release candidate:

Integrated Disk Encryption -- VMs that are delivered to XenClient from the Synchronizer can now be protected with AES-XTS disk encryption. This allows sensitive data to be fully protected when deployed on XenClient systems. In the event that a system is lost or stolen, all data can remain protected from unauthorized access.

External Monitor/Project Support -- The latest generation of Intel Core i5 and i7 vPro systems provide support for external monitors and projectors, which previously required running a VM with 3D graphics support enabled.

XenClient to Synchronizer Communication Hardening -- XenClient systems will now use client-side digital certificates along with user credentials to authenticate to the Synchronizer. All VHD files are encrypted with AES CBC encryption to allow secure delivery and caching of components over HTTP.

VM Switching Enhancements -- The in-guest VM switcher bar has been re-skinned with updated graphics and new pull-down behavior.

Revamped Synchronizer Web Interface -- The Synchronizer for XenClient has a revamped UI and refreshed graphics showing off the latest Citrix UI standards.

Where is VMware in all of this? Did Citrix beat them to the punch with a client-side bare-metal hypervisor? Well, sort of.

Back in July, VMware announced that it had changed its plans to create its own bare-metal client hypervisor and would instead concentrate its offline efforts on a hosted or Type-2 virtualization platform that would be included within VMware View 4.5. Doing so would better address the current install base and provide them with much broader coverage, VMware said. That's its claim to fame anyway.

It could also be that VMware realized just how hard it is to create and support a bare-metal client hypervisor and then make any money off it. If you thought supporting all the various server hardware out there was difficult, just ask Microsoft about supporting all the various versions of laptop and desktop hardware.

Now that Citrix is offering this new type of client hypervisor, will it make things easier or more difficult for organizations trying to decide their future desktop virtualization plans?

Bartoletti believes the biggest barrier to desktop virtualization is that the big vendors actually have too many solutions available. "Large customers get bogged down trying to figure out which mix of desktop virtualization strategies is right for each user type, while smaller companies might just look for a packaged out of the box solution. I think Citrix is protecting both flanks, and acting quite nimble," he added.

But things aren't all rainbows and pixie dust with this release. There are limitations with XenClient, as you might expect with any 1.0 release, and some of these limitations can prove quite frustrating.

The first limitation is the hardware support. Much like VMware ESX back in the early days of server virtualization, Citrix XenClient has a small number of supported platforms, according to the XenClient hardware compatibility list. There are 23 products officially supported; however, the system model alone does not imply support. There are nine different laptops in that list from Dell, eight from HP, and six from Lenovo. These laptops range from Intel Core 2 Duo to Intel Core i7 -- but the one thing they all have in common is that they must have Intel vPro technology in order to be considered compatible. For many folks that requirement could be a deal breaker -- and heaven forbid you try to use processors from Advanced Micro Devices!

Another frustrating limitation is the hardware requirements for supported graphic adapters, where the supported laptop machines are required to have Intel graphical processing units (GPUs). XenClient is only offering support on Intel's GMA 4500 or HD Graphic adapters. GPUs from other providers like ATI or Nvidia will not work.

In a world where we have contract workers with their own machines and employees operating under "buy your own PC" initiatives, client-side virtualization could be a great way to isolate and keep the organization's applications and information separate from users' personal files and apps. But the hardware and support restrictions currently imposed by XenClient 1.0 are probably going to be way too restrictive to generate wide acceptance.

But let's remember, this is a 1.0 product. Perhaps organizations will stick their big toe in the water to try it out, give feedback, and help Citrix expand its features and support. On the other hand, if organizations try it and have a negative experience, will that be enough to turn them off desktop virtualization? Let's hope that's not the case.